The warning message may appear because of problems with a website certificate. Certificate is a digital signature of a website. Certificates are used to establish encrypted connection between users and websites and to confirm website authenticity.

• The certificate has been revoked. The website owner can request revocation if the site was hacked. 
• The certificate was issued illegally. The certificate must be issued by a certification authority after the check. 
• Windows root certificates are not updated. For example, the DST Root CA X3 certificate, on which website certificates in a browser are based, expired on September 30, 2021. In this case:
  1. To see on which Windows root certificate the website certificate is based, click View certificate in the warning message.
  2. Go to the Certification Path tab.
  3. Update root certificates for Windows 7, 8, 8.1, 10, 11 using these instructions.
• The certificate chain is broken. The certificates are checked in a chain from the self-signed certificate to the trusted root certificate issued by the certification authority. The certificates in between are used for verification of other certificates in a chain.
  Possible causes of the broken certificates chain:
  • The chain consists of one self-signed certificate. Such certificates are not verified by the certification authority and cannot be trustworthy.
  • The chain does not end with a trusted root certificate.
  • The chain contains certificates which are not meant to sign other certificates.
  • The root or intermediate certificate has expired or its time has not come yet. The certification authority issues a certificate for a limited period of time. 
  • The chain cannot be built.
• The domain specified in the certificate does not match the website to which the connection is established.
• The certificate is not meant to confirm the node authenticity. For example, the certificate is intended only for encrypting the connection between the user and the website.
• Usage policy violation. The policy of the certificate is a set of rules which defines the use of the certificate with the specific security requirements. Each certificate must correspond to at least one policy. If there are several policies, the certificate must correspond to all of them. 
• Certificate structure is broken.
• An error has occurred when checking the certificate signature.

1. In the main window of your Kaspersky application, click .
2. Go to Security settings.

3. Go the Advanced settings section and select Network settings.

4. Click Trusted addresses → Add. 

5. Specify the website address that was displayed in the certificate warning message. Set the status to Active and click Add.

6. Click Save.
7. Click Save → Confirm.

1. In the main window of your Kaspersky application, click .
2. In the settings window, go to the Network settings section and select Trusted addresses (Manage exclusions in version 21.2 and earlier).

3. Click Add. 

 

4. Specify the website address that was displayed in the certificate warning message. Select the Active status and click Add.

 

5. Click Save.

6. Click Save → Yes.

1. Download the CA.zip archive.
2. Extract the files from it to the C:\CA folder. If there is no such folder, create it.
   Make sure that the files from the archive are located in this folder.
3. Open the command line as administrator using the instructions.
4. Run the command:

After running the command, a new line will appear. This means that the update was successful.

5. Restart your computer.

Root certificates will be updated. We also recommend to install all the available updates for Windows and the browser you are using.

If the issue persists, contact Kaspersky Customer Service.